A broad object of the invention is a compact dental handpiece or prophylaxis angle and dental tool combination that minimizes the passage of material such as abrasives from the open or tool-receiving end to the rotating parts and closed end.
Other dental handpieces are shown in Richmond U.S. Pat. No. 3,436,830, Baily 4,014,099, Fernald 1,170,523 and Heatherington 3,978,586 and the art cited in them. Cooper U.S. Pat. No. 2,469,261 purports to illustrate an arrangement by which a rubber cup can seal by compression, but the disclosure is different in that, among other things, the driving mechanism between the shaft and the rubber cup is part of the same mechanism that is supposed to give the sealing arrangement.
Objects of the present invention therefore include broadly the combination of a cross head for a dental handpiece and a dental tool that minimizes having granular or abrasive material reach the moving parts where it could abrade them. A specific object is a dental tool with a flexible flange or skirt means engageable in a cylindrical opening wherein it may seal by centrifugal force, and which is independent of the attachment of the tool to the handpiece.
A further object is to provide a dental tool with such a flexible flange seal that does not subject the sealing means to the thrust forces in use.
Further objects include the provision of a skirt arrangement that seals both when the instrument is at rest and when it is spinning. Specifically, it is an object to provide this with a single skirt. And more specifically it is an object to provide a three-point seal.